Molecular structural characteristics governing biocatalytic oxidation of PAHs with hemoglobin.

Based on some fundamental quantum chemical descriptors computed by PM3 hamiltonian, two quantitative structure-activity relationship (QSAR) models for biocatalytic oxidation specific activity of unmodified and chemically modified hemoglobin in the oxidation of different polycyclic aromatic hydrocarbons (PAHs) in 15% acetonitrile were developed, respectively, using partial least squares analysis (PLS). The cross-validated Q(cum)(2) values for the two optimal QSAR models are 0.785 and 0.747, respectively, indicating a good predictive ability for biocatalytic oxidation specific activity of PAHs. The main factors affecting specific activity of PAHs are most positive net atomic charges on a hydrogen atom (q(H)(+)), largest negative atomic charge on a carbon atom (q(C)(-)), dipole moment (μ), the energy of the highest occupied molecular orbital (E(HOMO)), and (E(LUMO) - E(HOMO))(2). The biocatalytic oxidation specific activity of PAHs with big q(C)(-) and (E(LUMO) - E(HOMO))(2) values tends to be slow. Increasing q(H)(+), μ, and E(HOMO) values of PAHs leads to increase of specific activity.